The O18 isotope effects on fructokinase and hexokinase will be measured by the equilibrium perturbation technique. The pH variation of the kinetic parameters will be measured in forward and reverse directions for yeast hexokinase, and NMR studies with Cr and Co nucleotides will be used to determine details of binding and catalysis. The absolute deuterium isotope effect on hydride transfer will be measured for glutamic dehydrogenase and norvaline from comparison of effects of deuterium and tritium substitution of V/K by the method of Northrop. Bibliographic references: Deuterium Isotope Effects and Substrate Specificity of Malic Enzyme. M.I. Schimerlik and W.W. Cleland. Federation Proc. 34, 495 (1975). Use of Chromium-ATP and Lyxose to Elucidate the Kinetic Mechanism and Coordination State of the Nucleotide Substrate for Yeast Hexokinase. K. D. Danenberg and W. W. Cleland. Biochemistry 14, 28 (1975).